JP5799487B2 - Spherical phosphor for wavelength conversion type solar cell encapsulant, wavelength conversion type solar cell encapsulant, solar cell module and production method thereof - Google Patents

Description

  The present invention relates to a spherical phosphor, a wavelength conversion type solar cell encapsulant using the same, a solar cell module using the same, and a method for producing them. More specifically, a solar cell module capable of increasing power generation efficiency by converting light in a wavelength region that does not contribute to power generation into light in a wavelength region that contributes to power generation, a wavelength conversion type solar cell sealing material used therefor, and these It is related with the manufacturing method.

  The conventional silicon crystal solar cell module has the following configuration. The protective glass on the surface (also referred to as cover glass) is made of tempered glass with a focus on impact resistance, and is in close contact with the sealing material (usually referred to as a resin or filler mainly composed of ethylene vinyl acetate copolymer). In order to improve the properties, one side has an uneven pattern by embossing.

Moreover, the uneven | corrugated pattern is formed inside, and the surface of a solar cell module is smooth. Moreover, the sealing material and back film for carrying out protection sealing of the photovoltaic cell and a tab wire are provided under the protective glass (for example, refer nonpatent literature 1).
A layer that emits light in the wavelength region that can contribute to power generation by converting the wavelength of ultraviolet or infrared light that does not contribute to power generation in the sunlight spectrum using a fluorescent substance (also referred to as a light emitting material) Many methods for providing the battery on the light receiving surface side have been proposed (see, for example, Patent Document 1).

In addition, a method for incorporating a rare earth complex, which is a fluorescent substance, in a sealing material has been proposed (see, for example, Patent Document 2).
Conventionally, ethylene-vinyl acetate copolymers imparted with thermosetting properties have been widely used as transparent sealing materials for solar cells (see, for example, Patent Document 3).

JP 2000-328053 A JP 2006-303033 A JP 2003-51605 A

Yasuhiro Sasakawa, “Solar Power Generation”-Latest Technology and System, 2000, CMC Corporation

  Patent Document 1 proposes wavelength conversion of light that does not contribute to power generation into light in a wavelength range that can contribute to power generation. The wavelength conversion layer contains a fluorescent material, but this fluorescent material is generally shaped. When the incident sunlight passes through the wavelength conversion film, the ratio of not reaching the solar cells and contributing to power generation increases. As a result, there is a problem that even if the light in the ultraviolet region is converted into the light in the visible region in the wavelength conversion layer, the ratio of the electric power generated relative to the incident sunlight (power generation efficiency) is not so high.

  Further, in the method described in Patent Document 3, the rare earth complex is easily hydrolyzed together with ethylene vinyl acetate (EVA) widely used as a sealing material and not only deteriorates but also wavelength-converted light. It is difficult to introduce to the solar battery cell. In addition, when the rare earth complex which is a fluorescent substance is dispersed in EVA, the rare earth metal molecules are easily aggregated and subject to hydrolysis, and the aggregate also scatters the excitation wavelength, thereby causing the rare earth as a fluorescent substance. There exists a problem that the utilization efficiency of a metal becomes very bad.

  The present invention is intended to improve the above-described problems, and improves the light utilization efficiency in the solar cell module, and makes it possible to stably improve the power generation efficiency, and a wavelength including the same. It is an object of the present invention to provide a conversion type solar cell encapsulant.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors converted light that does not contribute to solar power generation into a wavelength that contributes to power generation by using a spherical phosphor containing a fluorescent substance. At the same time, the present inventors have found that moisture resistance and heat resistance are excellent, dispersibility is good, and that incident sunlight can be efficiently introduced into a solar battery cell without scattering the fluorescent material, and the present invention has been completed. . Further, when a rare earth metal organic complex is used as the fluorescent material, the humidity resistance of the fluorescent material can be further improved.

That is, the present invention is as follows.
<1> As a fluorescent substance, a europium complex having at least one organic ligand selected from carboxylic acid, nitrogen-containing organic compound, nitrogen-containing aromatic heterocyclic compound, β-diketone, and phosphine oxide;
Transparent (meth) acrylic resin as a transparent material,
Volume average diameter Ri 10μm~500μm der,
The fluorescence wavelength converting solar cell encapsulant spherical phosphor content of Ru to 1% by mass 0.001% by weight of the material.
<2> The spherical phosphor according to <1>, wherein the transparent material has a refractive index lower than that of the phosphor and is 1.4 or more.
<3> The spherical phosphor according to <1> or <2>, wherein the vinyl monomer composition in which the fluorescent substance is dissolved or dispersed is spherical resin particles obtained by suspension polymerization.

< 4 > A wavelength conversion type solar cell encapsulant comprising a light-transmitting resin composition layer containing the spherical phosphor according to any one of <1> to < 3 > and an encapsulating resin.
< 5 > The wavelength-converting solar cell sealing material according to < 4 >, wherein the content of the spherical phosphor in the resin composition layer is 0.0001 to 10 mass percent.
< 6 > The wavelength conversion type solar cell encapsulating material according to < 4 > or < 5 >, further including a light transmissive layer other than the resin composition layer.
< 7 > m layers composed of the resin composition layer and a light transmissive layer other than the resin composition layer, and the refractive indexes of the m layers are set to n _{1 in} order from the light incident side. , N ₂ ,..., N _(m−1) , n _m , wherein n ₁ ≦ n ₂ ≦... ≦ n _(m−1) ≦ _nm , described in < 6 > above. Wavelength conversion type solar cell encapsulant .

A solar cell comprising < 8 > solar cell and the wavelength conversion solar cell sealing material according to any one of < 4 > to < 7 > disposed on a light receiving surface of the solar cell. module.
< 9 > A step of obtaining a spherical phosphor according to any one of <1> to <3> by suspension polymerization of a vinyl monomer composition in which a fluorescent substance is dissolved or dispersed, and the spherical phosphor. And a sheet forming step of forming a resin composition obtained by mixing or dispersing them in a sealing resin into a sheet shape.
< 10 > A method for producing a solar cell module having a plurality of light transmissive layers and solar cells, wherein the wavelength conversion type solar cell encapsulant according to any one of < 4 > to < 7 > is used. A method for producing a solar cell module, comprising the step of forming one of the light-transmitting layers by disposing the solar cell on the light-receiving surface side.

  ADVANTAGE OF THE INVENTION According to this invention, the light use efficiency in a solar cell module is improved, the spherical fluorescent substance which makes it possible to improve electric power generation efficiency stably, and the wavelength conversion type solar cell sealing material containing this are provided. be able to.

It is a conceptual diagram which shows an example of the relationship between the spherical fluorescent substance concerning a present Example, and incident light. It is a conceptual diagram which shows an example of the refraction of light in the interface from which a refractive index differs. It is a conceptual diagram which shows an example of the wavelength dependence of a refractive index. It is a figure which shows an example of the relationship between the spherical fluorescent substance content rate concerning a present Example, and electric power generation efficiency.

<Spherical phosphor and production method thereof>
The spherical phosphor of the present invention comprises a fluorescent substance and a spherical transparent material containing the fluorescent substance.
For example, the spherical phosphor is used by being contained in a wavelength-convertible resin composition layer constituting a wavelength-converting solar cell sealing material. For example, in a silicon crystal solar cell, light having a shorter wavelength than 400 nm or longer than 1200 nm is not effectively used in sunlight, and about 56% of solar energy does not contribute to power generation due to this spectrum mismatch. By using phosphors having a specific shape with excellent moisture resistance, heat resistance, good dispersibility, and suppressed concentration quenching, the present invention uses sunlight efficiently and stably by wavelength conversion. , Trying to overcome the spectral mismatch. Furthermore, it is intended to maximize the utilization efficiency of rare earth metal complexes as fluorescent materials and improve the effective luminous efficiency, thereby limiting the amount of expensive rare earth complexes to a very small amount and contributing to power generation. Can do.

  That is, the spherical phosphor of the present invention is a fluorescent material having excellent moisture resistance and heat resistance, good dispersibility, and suppressed concentration quenching. Such a fluorescent material can maximize the utilization efficiency of the rare earth metal complex, which is an expensive fluorescent substance, and can further improve the effective light emission efficiency and improve the power generation efficiency of the solar cell module. In addition, the spherical phosphor of the present invention, and the wavelength conversion type solar cell encapsulant using the same, simultaneously convert light that does not contribute to solar power generation into incident light that contributes to power generation, The scattering of the light can be suppressed and the light can be efficiently introduced into the solar battery cell.

In the present invention, since the fluorescent material is confined in the sphere, the ability of the fluorescent material can be maximized. This will be described with reference to the drawings. As shown in FIG. 2, when light travels from a high refractive medium to a low refractive medium, total reflection occurs at this interface according to its relative refractive index. Typical examples of the positive application of this phenomenon include optical devices such as optical fibers, optical waveguides, and semiconductor lasers. The condition for total reflection occurs when the incident angle is larger than the critical angle θc expressed by the following equation.
θ _c = sin ⁻¹ (n ₁ / n ₂ )

On the other hand, a substance has a specific refractive index, which has a dependency on the wavelength, and the refractive index increases from a long wavelength toward a short wavelength even in a transparent material. In particular, when a substance has absorption at a specific wavelength, the refractive index increases near that wavelength.
Further, in a fluorescent substance, transition from a ground state to an excited state occurs at an absorption wavelength (excitation wavelength), and energy is released as fluorescence (also referred to as light emission) when returning to the ground state. That is, by uniformly mixing a certain fluorescent substance with a transparent material, the refractive index distribution can be enhanced particularly in the excitation wavelength region as compared with the transparent material (for example, a transparent resin) as a base material.
This is conceptually shown in FIG. In the figure, the solid line represents the refractive index distribution of the transparent material as the matrix, and the broken line represents the refractive index distribution when the fluorescent material is contained therein. In particular, regarding the refractive index, by appropriately selecting a transparent material, a fluorescent material, and a medium (encapsulation resin) that are the sphere matrix, the refractive index in the sphere is changed to a medium (encapsulation resin) in the excitation wavelength region as shown in FIG. It is possible to obtain a correlation that is larger than that of the medium (sealing resin) in the emission wavelength region.

  In such a situation, light easily enters the sphere having a high refractive index in the excitation wavelength region. However, in the sphere, the refractive index of the sealing resin outside the sphere is low, so It becomes difficult to go outside the sphere, and total reflection is repeated inside the sphere. For this reason, it can be considered that the fluorescent substance contained in the sphere increases the use efficiency of excitation light. On the other hand, in the emission wavelength region, the difference between the refractive index of the sphere and the refractive index of the medium outside the sphere (for example, sealing resin) is not large, so that light is easily emitted outside the sphere. This state is conceptually shown in FIG.

By configuring the particles containing the fluorescent material into a spherical shape as described above, a sufficient amount of wavelength-converted light emission can be obtained even when an expensive fluorescent material is used in a small amount.
In addition, since the fluorescent material absorbs the excitation wavelength, the refractive index in the excitation wavelength region is high and light scattering is likely to occur. Further, when the fluorescent material is aggregated, light scattering is further increased, and the effect of improving the power generation efficiency by the intended wavelength conversion may not be sufficiently obtained. However, since the fluorescent material is encapsulated in a transparent material (preferably a transparent material having a lower refractive index than the fluorescent material), light scattering caused by the difference in refractive index between the fluorescent material and the sealing resin is effectively prevented. Can be suppressed.

Furthermore, when a substance having low moisture resistance such as a rare earth complex is used as the fluorescent substance, the moisture resistance can be further improved by confining the substance in a sphere of a transparent material (preferably a moisture-resistant transparent material).
The spherical phosphor of the present invention can be suitably used for a solar cell module. Besides, wavelength-converted agricultural materials, various optical devices for light emitting diode excitation, display devices, various optical devices for laser excitation, The present invention can be applied to display devices and the like, and the present invention does not limit the application.

The spherical phosphor of the present invention includes at least one fluorescent substance described later and at least one transparent material, and has a spherical shape.
The particle diameter of the spherical phosphor can be appropriately selected according to the purpose. For example, when used for a wavelength conversion type solar cell encapsulant, it can be 1 to 1000 μm, and 10 to 500 μm. Is preferred.

(Fluorescent substance)
The fluorescent material used in the present invention can be appropriately selected according to the purpose. For example, the fluorescent material is preferably a fluorescent material having an excitation wavelength of 500 nm or less and an emission wavelength longer than that. More preferably, the compound is capable of converting light outside the wavelength range that can be used in the solar cell into a wavelength range that can be used in the solar cell.
Specific examples of the fluorescent substance include organic phosphors, inorganic phosphors, and rare earth metal complexes. Among these, from the viewpoint of wavelength conversion efficiency, at least one of an organic phosphor and a rare earth metal complex is preferable, and a rare earth metal complex is more preferable.

-Inorganic phosphor-
Examples of the inorganic phosphor include, for example, fluorescent particles of Y ₂ O ₂ S: Eu, Mg, Ti, oxyfluoride crystallized glass containing Er ³⁺ ions, compounds composed of strontium oxide and aluminum oxide, and rare earth elements. Europium (Eu) and dysprosium (Dy) added SrAl ₂ O ₄ : Eu, Dy, Sr ₄ Al _{1 4} O ₂₅ : Eu, Dy, CaAl ₂ O ₄ : Eu, Dy, ZnS: Cu, etc. An inorganic fluorescent material can be mentioned.

-Organic phosphor-
Examples of the organic phosphor include organic dyes such as cyanine dyes, pyridine dyes, and rhodamine dyes, BASF Lumogen F Violet 570, Yellow083, Orange 240, Red300, and Taoka Chemical Industries, Ltd. Organic phosphors such as basic dye Rhodamine B, Sumiplast Yellow FL7G manufactured by Sumika Finechem Co., Ltd., MACROLEX Fluorescent Red G manufactured by Bayer, and Yellow 10GN may be used.

-Rare earth metal complex-
The metal constituting the rare earth metal complex is preferably at least one of europium and samarium, and more preferably europium, from the viewpoint of luminous efficiency.
The ligand constituting the rare earth metal complex is not particularly limited as long as it can coordinate to the rare earth metal, and can be appropriately selected according to the metal to be used. Among these, from the viewpoint of luminous efficiency, an organic ligand is preferable, and an organic ligand capable of forming a complex with at least one of europium and samarium is preferable.

In the present invention, although the ligand is not limited, the neutral ligand is selected from carboxylic acid, nitrogen-containing organic compound, nitrogen-containing aromatic heterocyclic compound, β-diketone, and phosphine oxide. It is preferable that it is at least one kind.
In addition, as a ligand of the rare earth complex, a general formula R ¹ COCHR ² COR ³ (wherein R ¹ represents an aryl group, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group, or a substituent thereof, R ² Represents a hydrogen atom, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group or an aryl group, and R ³ represents an aryl group, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group or a substituent thereof. (Beta) -diketone represented by this may be contained.

Specific examples of β-diketones include acetylacetone, perfluoroacetylacetone, benzoyl-2-furanoylmethane, 1,3-di (3-pyridyl) -1,3-propanedione, benzoyltrifluoroacetone, and benzoylacetone. , 5-chlorosulfonyl-2-thenoyltrifluoroacetone, bis (4-bromobenzoyl) methane, dibenzoylmethane, d, d-dicamphorylmethane, 1,3-dicyano-1,3-propanedione, p- Bis (4,4,5,5,6,6,6-heptafluoro-1,3-hexanedinoyl) benzene, 4,4'-dimethoxydibenzoylmethane, 2,6-dimethyl-3,5-heptane Dione, dinaphthoylmethane, dipivaloylmethane, bis (perfluoro-2-propoxypropionyl) me 1,3-di (2-thienyl) -1,3-propanedione, 3- (trifluoroacetyl) -d-camphor, 6,6,6-trifluoro-2,2-dimethyl-3,5 -Hexanedione, 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione, 6,6,7,7,8,8,8-heptafluoro -2,2-dimethyl-3,5-octanedione, 2-furyltrifluoroacetone, hexafluoroacetylacetone, 3- (heptafluorobutyryl) -d-camphor, 4,4,5,5,6,6 6-heptafluoro-1- (2-thienyl) -1,3-hexanedione, 4-methoxydibenzoylmethane, 4-methoxybenzoyl-2-furanoylmethane, 6-methyl-2,4-heptanedione, 2 -Naftoytri Fluoroacetone, 2- (2-pyridyl) benzimidazole, 5,6-dihydroxy-1,10-phenanthroline, 1-phenyl-3-methyl-4-benzoyl-5-pyrazole, 1-phenyl-3-methyl-4 -(4-butylbenzoyl) -5-pyrazole, 1-phenyl-3-methyl-4-isobutyryl-5-pyrazole, 1-phenyl-3-methyl-4-trifluoroacetyl-5-pyrazole, 3- (5 -Phenyl-1,3,4-oxadiazol-2-yl) -2,4-pentanedione, 3-phenyl-2,4-pentanedione, 3- [3 ', 5'-bis (phenylmethoxy) Phenyl] -1- (9-phenanthyl) -1-propane-1,3-dione, 5,5-dimethyl-1,1,1-trifluoro-2,4-hexanedione, 1- Phenyl-3- (2-thienyl) -1,3-propanedione, 3- (t-butylhydroxymethylene) -d-camphor, 1,1,1-trifluoro-2,4-pentanedione, 1,1 , 1,2,2,3,3,7,7,8,8,9,9,9-tetradecafluoro-4,6-nonanedione, 2,2,6,6-tetramethyl-3,5- Heptanedione, 4,4,4-trifluoro-1- (2-naphthyl) -1,3-butanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 2, 2,6,6-tetramethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-octanedione, 2,2,6-trimethyl-3,5-heptanedione, , 2,7-Trimethyl-3,5-octanedione, 4,4,4- Lifluoro-1- (thienyl) -1,3-butanedione (TTA), 1- (pt-butylphenyl) -3- (N-methyl-3-pyrrole) -1,3-propanedione (BMPP), 1- (pt-Butylphenyl) -3- (p-methoxyphenyl) -1,3-propanedione (BMDBM), 1,3-diphenyl-1,3-propanedione, benzoylacetone, dibe down benzoyl acetone, diisobutyronitrile yl methane, di pin bar Roirumetan, 3-methyl pentane-2,4-dione, 2,2-dimethyl pentane-3,5-dione, 2-methyl-1,3-butanedione, 1, 3-butanedione, 3-phenyl-2,4-pentanedione, 1,1,1-trifluoro-2,4-pentanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4- Xanthedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 3-methyl-2,4-pentanedione, 2-acetylcyclopentanone, 2-acetylcyclohexanone, 1-heptafluoropropyl-3 -T-butyl-1,3-propanedione, 1,3-diphenyl-2-methyl-1,3-propanedione, 1-ethoxy-1,3-butanedione, and the like can be given.

  Nitrogen-containing organic compounds, nitrogen-containing aromatic heterocyclic compounds, and phosphine oxides of neutral ligands of rare earth complexes include, for example, 1,10-phenanthroline, 2-2'-bipyridyl, 2-2'-6, 2 "-terpyridyl, 4,7-diphenyl-1,10-phenanthroline, 2- (2-pyridyl) benzimidazole, triphenylphosphine oxide, tri-n-butylphosphine oxide, tri-n-octylphosphine oxide, tri- Examples include n-butyl phosphate.

As the rare earth complex having the above-described ligand, for example, Eu (TTA) ₃ phen, Eu (BMPP) ₃ phen, Eu (BMDBM) ₃ phen or the like can be preferably used from the viewpoint of wavelength conversion efficiency.
A method for producing Eu (TTA) ₃ Phen is described, for example, in Masa Mitsui, Shinji Kikuchi, Tokuji Miyashita, Yutaka Amano, J. et al. Mater. Chem. Reference may be made to the method disclosed in 2003, 13, 285-2879.

  In the present invention, a solar cell module having high power generation efficiency can be configured by using a europium complex as the fluorescent material. The europium complex converts light in the ultraviolet region into light in the red wavelength region with high wavelength conversion efficiency, and the converted light contributes to power generation in the solar battery cell.

  There is no restriction | limiting in particular as content of the fluorescent substance in the spherical fluorescent substance of this invention, Although it can select suitably according to the objective and the kind of fluorescent substance, it is 0 with respect to the total mass of a spherical fluorescent substance from a viewpoint of electric power generation efficiency. 0.001 to 1% by mass is preferable, and 0.01 to 0.5% by mass is more preferable.

(Transparent material)
In the present invention, the fluorescent substance is contained in a transparent material. In the present invention, “transparent” means that the transmittance of light having a wavelength of 400 to 800 nm at an optical path length of 1 cm is 90% or more.
The transparent material is not particularly limited as long as it is transparent, and examples thereof include resins such as acrylic resin, methacrylic resin, urethane resin, epoxy resin, polyester, polyethylene, and polyvinyl chloride. Among these, acrylic resins and methacrylic resins are preferable from the viewpoint of suppressing light scattering. Although there is no restriction | limiting in particular as a monomer compound which comprises the said resin, From a viewpoint of light scattering suppression, it is preferable that it is a vinyl compound.

Further, as a method of making the transparent material contain the fluorescent material and making the shape spherical, for example, a composition is prepared by dissolving or dispersing the fluorescent material in a monomer compound, and this is polymerized (emulsion polymerization or (Suspension polymerization). Specifically, for example, a mixture containing a fluorescent substance and a vinyl compound is prepared, and this is emulsified or dispersed in a medium (for example, an aqueous medium) to obtain an emulsion or suspension. For example, by using a radical polymerization initiator to polymerize a vinyl compound contained in an emulsion or suspension (emulsion polymerization or suspension polymerization), a spherical phosphor is obtained as a spherical resin particle containing a fluorescent substance. Can be configured.
In the present invention, from the viewpoint of power generation efficiency, a mixture containing a fluorescent substance and a vinyl compound is prepared, and this is dispersed in a medium (for example, an aqueous medium) to obtain a suspension. It is preferable to form a spherical phosphor as spherical resin particles containing a fluorescent substance by polymerizing (suspension polymerization) a vinyl compound contained in the suspension using an initiator.

(Vinyl compound)
In the present invention, the vinyl compound is not particularly limited as long as it is a compound having at least one ethylenically unsaturated bond, and an acrylic monomer, a methacrylic monomer, which can be converted into a vinyl resin, particularly an acrylic resin or a methacrylic resin when polymerized. An acrylic oligomer, a methacryl oligomer, etc. can be used without a restriction | limiting in particular. In the present invention, an acrylic monomer, a methacryl monomer, and the like are preferable.

  Examples of the acrylic monomer and the methacrylic monomer include acrylic acid, methacrylic acid, and alkyl esters thereof, and other vinyl compounds that can be copolymerized with these may be used in combination. A combination of the above can also be used.

  Examples of the alkyl acrylate ester and the alkyl methacrylate ester include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate. Acrylic acid unsubstituted alkyl ester and methacrylic acid unsubstituted alkyl ester; dicyclopentenyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate; benzyl (meth) acrylate; α, β-unsaturated carboxylic acid to polyhydric alcohol (For example, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), trimethylolpropane di (meth) acrylate, trimethylolpropylene) N-tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polypropylene glycol di (meth) Acrylate (having 2 to 14 propylene groups), dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A polyoxyethylene di (meth) acrylate, bisphenol A dioxyethylene di ( Meth) acrylate, bisphenol A trioxyethylene di (meth) acrylate, bisphenol A decaoxyethylene di (meth) acrylate, etc.); Compounds obtained by adding an α, β-unsaturated carboxylic acid to a group-containing compound (for example, trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.); a polyvalent carboxylic acid (for example, phthalic anhydride) Acid) and a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl (meth) acrylate); acrylic acid or alkyl ester of methacrylic acid (for example, (meth) acrylic acid methyl ester, ( (Meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid 2-ethylhexyl ester); urethane (meth) acrylate (eg, tolylene diisocyanate and 2-hydroxyethyl (meth) acrylic ester) reaction A reaction product of trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylic acid ester, etc.]; an acrylic acid-substituted alkyl ester or a methacrylic acid in which a hydroxyl group, an epoxy group, a halogen group or the like is substituted on these alkyl groups Acid-substituted alkyl ester; and the like.

  Examples of other vinyl compounds that can be copolymerized with acrylic acid, methacrylic acid, alkyl acrylate ester, or alkyl methacrylate ester include acrylamide, acrylonitrile, diacetone acrylamide, styrene, vinyl toluene, and the like. These vinyl monomers can be used alone or in combination of two or more.

  The vinyl compound in the present invention can be appropriately selected so that the refractive index of the resin particles to be formed has a desired value, and at least one selected from an alkyl acrylate ester and an alkyl methacrylate ester is used. preferable.

(Radical polymerization initiator)
In the present invention, it is preferable to use a radical polymerization initiator in order to polymerize the vinyl compound. As the radical polymerization initiator, a commonly used radical polymerization initiator can be used without particular limitation. For example, a peroxide etc. are mentioned preferably. Specifically, organic peroxides or azo radical initiators that generate free radicals by heat are preferred.
Examples of the organic peroxide include isobutyl peroxide, α, α′-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, di-n-propylperoxydicarbonate, and bis-s-. Butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl neodecanoate, bis (4-t-butylcyclohexyl) peroxydicarbonate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate Bis-2-ethoxyethyl peroxydicarbonate, bis (ethylhexyl ) peroxydicarbonate, t-hexyl neodecanoate, bismethoxybutyl peroxydicarbonate, bis (3-methyl-3-methoxybutyl ) peroxy Dicarbonate, t-butyl pero Cineodecanoate, t-hexylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylper 2-ethyl hexanoate, succinate Nick peroxide, 2,5-dimethyl-2,5-bis (2-ethyl hexanoyl) hexane, 1-cyclohexyl-1-methylethyl peroxy-2-ethylhex Noeto, t-hexyl peroxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t- butyl peroxy-2-ethylhexanoate, m- torr Oy Reuben benzoyl peroxide, benzoyl peroxide, t -Butyl peroxyisobutyrate, 1, 1-bis (t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexanone, 2,2-bis (4,4-dibutylperoxy) (Cyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexa Noate, t-butyl peroxylaurate, 2,5-dimethyl-2,5-bis (m-toluoyl pero Ii) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butyl peroxyacetate, 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t- Butyl peroxyisophthalate, α, α ′ bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butyl kumi peroxide, di -t- Buchirupaoki side, p- menthane hydroperoxide Oki Side, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, Cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane and the like can be used.

  Examples of the azo radical initiator include azobisisobutyronitrile (AIBN, trade name V-60, manufactured by Wako Pure Chemical Industries), 2,2′-azobis (2-methylisobutyronitrile) (trade name). V-59, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name V-65, manufactured by Wako Pure Chemical Industries, Ltd.), dimethyl-2,2′-azobis (isobutyrate) ) (Trade name V-601, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (trade name V-70, manufactured by Wako Pure Chemical Industries, Ltd.), and the like. It is done.

  The usage-amount of a radical polymerization initiator can be suitably selected according to the kind of said vinyl compound, the refractive index of the resin particle formed, etc., and is used by the usage-amount normally used. Specifically, for example, it can be used at 0.01 to 2% by weight, preferably 0.1 to 1% by weight, based on the vinyl compound.

  The refractive index of the transparent material in the present invention is not particularly limited, but is preferably lower than the refractive index of the fluorescent material, lower than the refractive index of the fluorescent material, and sealed later, from the viewpoint of suppressing light scattering. More preferably, the ratio of the refractive index of the stop resin is close to 1. Generally, the refractive index of the fluorescent material is larger than 1.5, and the refractive index of the sealing resin is about 1.4 to 1.5. Therefore, the refractive index of the transparent material is 1.4 to 1.5. Preferably there is.

  The spherical phosphor preferably has a refractive index higher than that of the sealing resin serving as a dispersion medium at the excitation wavelength of the fluorescent material and lower than that of the sealing resin at the emission wavelength. By being this mode, the light utilization efficiency in the excitation wavelength region is further improved.

<Wavelength conversion solar cell encapsulant>
The wavelength conversion type solar cell encapsulant of the present invention is a light transmissive resin having wavelength conversion ability used as one of the light transmissive layers of a solar cell module having a plurality of light transmissive layers and solar cells. At least one layer of the composition is provided. The resin composition layer includes at least one of the spherical phosphors and at least one of a sealing resin (preferably a transparent sealing resin), and the spherical phosphor is dispersed in the sealing resin. Yes.
When the wavelength conversion type solar cell encapsulant includes the resin composition layer containing the spherical phosphor, when used as one of the light transmissive layers in the solar cell module, the light utilization efficiency is improved, The power generation efficiency can be improved stably.

Light scattering correlates with the ratio between the refractive index of the spherical phosphor and the refractive index of the sealing resin. Specifically, the light scattering is less affected by the particle size of the spherical phosphor if the ratio of the refractive index of the spherical phosphor to the refractive index of the transparent sealing resin is close to “1”. Light scattering is also small. In particular, when the present invention is applied to a wavelength conversion type light transmission layer of a solar cell module, it is preferable that the refractive index ratio in a wavelength region sensitive to solar cells, that is, 400 to 1200 nm is close to “1”. On the other hand, in spherical fluorescent body to cause total reflection of the excitation wavelength range of the light efficiently, the refractive index of the spherical-shaped phosphor is higher than the refractive index of the sealing resin is a medium in an excitation wavelength region It is preferable to become.

In view of the above requirements, for example, Eu (TTA) ₃ phen as a fluorescent substance, polymethyl methacrylate as a transparent material (sphere base material), and ethylene-vinyl acetate copolymer (EVA) as a sealing resin are used. Thus, particularly good refractive index correlation can be given from the viewpoints of excitation wavelength and emission wavelength, and also from the viewpoint of solar cell sensitivity.
However, in the present invention, it is preferable to appropriately select each so that the mutual relationship in the respective refractive indexes of the fluorescent material, the transparent material, and the sealing resin satisfies the above conditions, and only in the above combinations. It is not limited.

  The preferred blending amount of the spherical phosphor in the wavelength-converting resin composition layer provided in the wavelength-converting solar cell encapsulating material of the present invention is 0.0001 to 10% by mass with respect to the total nonvolatile content. preferable. Luminous efficiency improves by setting it as 0.0001 mass% or more. Moreover, by setting it as 10 mass% or less, scattering of incident light is suppressed more effectively, and a power generation effect improves more.

(Sealing resin)
The wavelength-convertible resin composition layer in the present invention contains a sealing resin (transparent sealing resin). As the transparent sealing resin, a photocurable resin, a thermosetting resin, a thermoplastic resin, or the like is preferably used.
Conventionally, as a resin used as a transparent sealing material for solar cells, an ethylene-vinyl acetate copolymer (EVA) imparted with thermosetting properties is widely used as described in Patent Document 3 described above. However, the present invention is not limited to this.

  When a photocurable resin is used for the dispersion medium resin (transparent sealing resin) of the resin composition for wavelength conversion type solar cell encapsulant, the resin configuration and photocuring method of the photocurable resin are not particularly limited. For example, in the photocuring method using a photoradical initiator, the wavelength-converting solar cell encapsulant resin composition includes (A) a photocurable resin, (B) a crosslinkable monomer, and (C ) A dispersion medium resin containing a photoinitiator that generates free radicals by light.

  Here, as the photocurable resin (A), a copolymer obtained by copolymerizing acrylic acid or methacrylic acid and alkyl esters thereof and other vinyl monomers copolymerizable therewith as constituent monomers is used. These copolymers can be used alone or in combination of two or more. Examples of the alkyl acrylate or alkyl methacrylate include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and the like. Acrylic acid unsubstituted alkyl ester or methacrylic acid unsubstituted alkyl ester, acrylic acid substituted alkyl ester or methacrylic acid substituted alkyl ester in which a hydroxyl group, an epoxy group, a halogen group or the like is substituted on these alkyl groups.

  Examples of other vinyl monomers that can be copolymerized with acrylic acid, methacrylic acid, alkyl acrylate ester, or alkyl methacrylate ester include acrylamide, acrylonitrile, diacetone acrylamide, styrene, vinyl toluene, and the like. These vinyl monomers can be used alone or in combination of two or more. Moreover, it is preferable that the weight average molecular weight of the dispersion medium resin of (A) component is 10,000-300,000 from the point of coating-film property and coating-film intensity | strength.

  (B) As the crosslinkable monomer, for example, a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid (for example, polyethylene glycol di (meth) acrylate (the number of ethylene groups is 2 to 14). ), Trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, Tetramethylolmethane tetra (meth) acrylate, polypropylene glycol di (meth) acrylate (having 2 to 14 propylene groups), dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) ) Acrylate, bisphenol A polyoxyethylene di (meth) acrylate, bisphenol A dioxyethylene di (meth) acrylate, bisphenol A trioxyethylene di (meth) acrylate, bisphenol A deoxyoxyethylene di (meth) acrylate, etc.]; glycidyl Compounds obtained by adding an α, β-unsaturated carboxylic acid to a group-containing compound (for example, trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.); a polyvalent carboxylic acid (for example, phthalic anhydride) Acid) and an esterified product of a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl (meth) acrylate); an alkyl ester of acrylic acid or methacrylic acid (for example, (meth) acrylate) Methyl laurate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid 2-ethylhexyl ester); urethane (meth) acrylate (eg tolylene diisocyanate and 2-hydroxyethyl (meth) ) A reaction product with an acrylic ester, a reaction product of trimethylhexamethylene diisocyanate, cyclohexane dimethanol, and 2-hydroxyethyl (meth) acrylic ester), and the like.

  Particularly preferred (B) crosslinkable monomers are trimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate in the sense that the crosslinking density and reactivity can be easily controlled. Bisphenol A polyoxyethylene dimethacrylate. In addition, the said compound is used individually or in combination of 2 or more types.

  As will be described later, in particular, when the refractive index of the wavelength conversion type solar cell encapsulant or its lower layer (the side in contact with the solar cell) is increased, (A) a photocurable resin and / or (B) cross-linking It is advantageous that the functional monomer contains bromine and sulfur atoms. Examples of the bromine-containing monomer include New Frontier BR-31, New Frontier BR-30, New Frontier BR-42M manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and the like. Examples of the sulfur-containing monomer composition include IU-L2000, IU-L3000, and IU-MS1010 manufactured by Mitsubishi Gas Chemical Company. However, the bromine and sulfur atom-containing monomers (polymers containing them) used in the present invention are not limited to those listed here.

  (C) The photoinitiator is preferably a photoinitiator that generates free radicals by ultraviolet light or visible light. For example, benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, and benzoin phenyl ether Benzophenones such as benzophenone, N, N'-tetramethyl-4,4'-diaminobenzophenone (Michler ketone), N, N'-tetraethyl-4,4'-diaminobenzophenone, benzyldimethyl ketal (Ciba Japan) IRGACURE (Irgacure) 651), benzyl ketals such as benzyl diethyl ketal, 2,2-dimethoxy-2-phenylacetophenone, p-tert-butyldichloroacetophenone, p-di Acetophenones such as tilaminoacetophenone, xanthones such as 2,4-dimethylthioxanthone and 2,4-diisopropylthioxanthone, or hydroxycyclohexyl phenyl ketone (manufactured by Ciba Japan, IRGACURE (Irgacure) 184), 1- (4- Isopropylphenyl) -2-vitroxy-2-methylpropan-1-one (Ciba Japan, Darocur 1116), 2-hydroxy-2-methyl-1-phenylpropan-1-one (Ciba Japan) Darocur 1173) and the like, and these may be used alone or in combination of two or more.

  Examples of (C) photoinitiators that can be used as photoinitiators include 2,4,5-triallylimidazole dimer, 2-mercaptobenzoxazole, leucocrystal violet, and tris (4-diethylamino-2). Combinations with -methylphenyl) methane and the like are also mentioned. In addition, although it does not itself have photoinitiating properties, it can be used in combination with the above-mentioned substances to provide a sensitizer system with better photoinitiating performance as a whole, such as triethanolamine for benzophenone. Secondary amines can be used.

Moreover, what is necessary is just to change the said (C) photoinitiator into a thermal initiator in order to make sealing resin thermosetting.
(C) The thermal initiator is preferably an organic peroxide that generates free radicals by heat. For example, isobutyl peroxide, α, α′bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecano Bis-n-propyl peroxydicarbonate, bis-s-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl neodecanoate, bis (4-t-butylcyclohexyl) peroxydi Carbonate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, di-2-ethoxyethylperoxydicarbonate, bis (ethylhexyl ) peroxydicarbonate, t-hexylneodecanoate, bismethoxybutylperoxy Dicarbonate, bis (3-methyl-3 Methoxybutyl) peroxydicarbonate, t- butyl peroxyneodecanoate, t-hexyl peroxypivalate, 3,5,5-trimethyl hexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide , 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, succinate Nick peroxide, 2,5-dimethyl-2,5-di (2-ethyl hexanoyl) hexane, 1- Cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m - torr OY Reuben benzoyl peroxide, benzoin Ruperoxide, t-butylperoxyisobutyrate, 1,1-bis (t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexanone 2,2-bis (4,4-dibutylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate 2,5-dimethyl-2,5-di (m-toluoylperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl -4,4-bis (t-butylperoxy) valerate, di-t-butylperoxyisophthalate, α, α'bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl -2,5-bis (t-butylperoxy) hexane, t-butylcumyl peroxide, Di -t- Buchirupaoki side, p- menthane hydroperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne, diisopropyl benzene hydroperoxide, t- butyl trimethylsilyl peroxide, 1,1 , 3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, etc. can be used. .

  The above is an example of the acrylic photocurable resin and the thermosetting resin, but the epoxy photocurable resin and the thermosetting resin that are usually used are also included in the wavelength conversion type solar cell encapsulant of the present invention. It can be used as a dispersion medium resin. However, since the curing of the epoxy is ionic, the coated phosphor or the rare earth metal complex that is a fluorescent substance may be affected and may cause deterioration or the like. Therefore, an acrylic type is more preferable.

  When a thermoplastic resin that flows by heating or pressurization is used for the dispersion medium resin of the resin composition for wavelength conversion type solar cell encapsulant, for example, natural rubber, polyethylene, polypropylene, polyvinyl acetate, polyisoprene, poly- (Di) enes such as 1,2-butadiene, polyisobutene, polybutene, poly-2-heptyl-1,3-butadiene, poly-2-t-butyl-1,3-butadiene, poly-1,3-butadiene , Polyethers such as polyoxyethylene, polyoxypropylene, polyvinyl ethyl ether, polyvinyl hexyl ether, and polyvinyl butyl ether, polyesters such as polyvinyl acetate and polyvinyl propionate, polyurethane, ethyl cellulose, polyvinyl chloride, polyacrylonitrile, polymethacrylate Ronitrile, poly Sulfone, phenoxy resin, polyethyl acrylate, polybutyl acrylate, poly-2-ethylhexyl acrylate, poly-t-butyl acrylate, poly-3-ethoxypropyl acrylate, polyoxycarbonyl tetramethacrylate, polymethyl acrylate, polyisopropyl methacrylate, poly Dodecyl methacrylate, polytetradecyl methacrylate, poly-n-propyl methacrylate, poly-3,3,5-trimethylcyclohexyl methacrylate, polyethyl methacrylate, poly-2-nitro-2-methylpropyl methacrylate, poly-1,1-diethyl Poly (meth) acrylic acid esters such as propyl methacrylate and polymethyl methacrylate can be used as the dispersion medium resin.

  Two or more kinds of these thermoplastic resins may be copolymerized as required, or two or more kinds may be blended and used.

  Furthermore, epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate, or the like can be used as a copolymer resin with the above resin. In particular, urethane acrylate, epoxy acrylate, and polyether acrylate are excellent from the viewpoint of adhesiveness.

  As epoxy acrylate, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl alcohol diglycidyl ether, resorcinol diglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, polyethylene glycol diglycidyl ether And (meth) acrylic acid adducts such as trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, and sorbitol tetraglycidyl ether.

  A polymer having a hydroxyl group in the molecule, such as epoxy acrylate, is effective in improving adhesion. These copolymer resins can be used in combination of two or more as required. The softening temperature of these resins is preferably 200 ° C. or less, and more preferably 150 ° C. or less from the viewpoint of handleability. Considering that the use environment temperature of the solar cell unit is usually 80 ° C. or lower and workability, the softening temperature of the resin is particularly preferably 80 to 120 ° C.

The composition of the other resin composition when the thermoplastic resin is used as the dispersion medium resin is not particularly limited as long as the above-described coated phosphor is contained, but usually used components such as a plasticizer, a flame retardant, It is possible to contain a stabilizer and the like.
As the dispersion medium resin of the wavelength conversion type solar cell encapsulant of the present invention, as described above, photocurability, thermosetting, thermoplasticity, and the resin is not particularly limited, but as a particularly preferable resin, The composition which mix | blended the thermal radical initiator with the ethylene-vinyl acetate copolymer widely utilized as the sealing material for conventional solar cells is mentioned.

The wavelength conversion type solar cell encapsulant of the present invention may be composed only of a wavelength convertible resin composition layer containing a spherical phosphor and an encapsulating resin, but in addition to this, the resin composition layer It is preferable to further have a light transmission layer other than the above.
Examples of the light-transmitting layer other than the resin composition layer include a light-transmitting layer obtained by removing the spherical phosphor from the wavelength-converting resin composition layer.
When the wavelength conversion type solar cell encapsulating material of the present invention is composed of a plurality of light transmissive layers, it is preferable that the wavelength conversion type solar cell encapsulating material has at least the same or higher refraction than the layer on the incident side.
In detail, m light-transmitting layers are layer 1, layer 2,..., Layer (m−1), layer m in order from the light incident side, and the refractive indices of the respective layers are sequentially n _{1. , n 2, ···, n (} m-1), when the _{n m,} it is preferable _{that n 1 ≦ n 2 ≦ ··· ≦} n (m-1) ≦ n m holds.

  Although there is no restriction | limiting in particular as a refractive index of the wavelength conversion type solar cell sealing material of this invention, Preferably it is 1.5-2.1, More preferably, you may be 1.5-1.9. Moreover, when the wavelength conversion type solar cell sealing material of this invention consists of a some light transmissive layer, it is preferable that the whole refractive index of the wavelength conversion type solar cell sealing material is in the said range.

  It is preferable that the wavelength conversion type solar cell sealing material of this invention is arrange | positioned on the light-receiving surface of a photovoltaic cell. By doing so, it is possible to follow the uneven structure including the texture structure of the solar cell light receiving surface, the cell electrode, the tab line and the like without a gap.

<Method for Producing Wavelength Conversion Type Solar Cell Sealant>
The method for producing a wavelength conversion type solar cell encapsulant of the present invention includes (1) a step of suspension polymerization of a vinyl monomer composition in which a fluorescent substance is dissolved or dispersed to obtain a spherical phosphor, and (2) And a sheet forming step of forming a resin composition obtained by mixing or dispersing the spherical phosphor in a sealing resin (transparent sealing resin) into a sheet shape.
The details of the step of obtaining the spherical phosphor are as described above. Moreover, the sheet | seat formation process can use the method normally used as a method of forming a resin composition in a sheet form without a restriction | limiting in particular.
The wavelength conversion type solar cell encapsulant of the present invention is preferably formed in a sheet shape from the viewpoint of ease of use.

  In the present invention, a step of obtaining a spherical phosphor by suspension polymerization of a vinyl monomer composition in which a fluorescent substance (preferably a europium complex) is dissolved or dispersed, and (2) sealing the spherical phosphor It is preferable that it is a manufacturing method including the sheet | seat formation process which forms the resin composition obtained by disperse | distributing to resin (transparent sealing resin) in a sheet form.

<Solar cell module>
The present invention also includes a solar module including the wavelength conversion type solar cell encapsulant. The solar cell module of this invention is equipped with the photovoltaic cell and the said wavelength conversion type solar cell sealing material arrange | positioned on the light-receiving surface of the said photovoltaic cell. This improves power generation efficiency.
The wavelength conversion type solar cell encapsulant of the present invention is used as one of light transmissive layers of a solar cell module having a plurality of light transmissive layers and solar cells, for example.

  In this invention, a solar cell module is comprised from required members, such as an antireflection film, protective glass, a wavelength conversion type solar cell sealing material, a photovoltaic cell, a back film, a cell electrode, a tab wire, for example. Among these members, the light-transmitting layer having light transmittance includes an antireflection film, a protective glass, the wavelength conversion type solar cell sealing material of the present invention, a SiNx: H layer and a Si layer of the solar cell, and the like. Can be mentioned.

  In the present invention, the order of lamination of the light-transmitting layers mentioned above is usually an antireflection film, protective glass, and the wavelength conversion type solar cell sealing of the present invention, which are formed in order from the light receiving surface of the solar cell module. The material is a SiNx: H layer or Si layer of the solar battery cell.

  That is, in the wavelength conversion type solar cell encapsulant of the present invention, the external light entering from any angle has little reflection loss, and the refractive index of the wavelength conversion type solar cell encapsulant is efficiently introduced into the solar cell. The light-transmitting layer disposed on the light incident side from the wavelength conversion type solar cell encapsulant, that is, higher than the refractive index of the antireflection film, protective glass, etc., and the reflection of the wavelength conversion type solar cell encapsulant The refractive index of the light transmissive layer disposed on the incident side, that is, the SiNx: H layer (also referred to as “cell antireflection film”) and the Si layer of the solar battery cell is preferably lower.

  Specifically, the light transmitting layer disposed on the light incident side from the wavelength conversion type solar cell encapsulant, that is, the refractive index of the antireflection film is 1.25 to 1.45, and the refractive index of the protective glass is Usually, about 1.45 to 1.55 is used. The refractive index of the light transmissive layer disposed on the light incident side of the wavelength conversion type solar cell encapsulant, that is, the SiNx: H layer (cell antireflection film) of the solar cell is usually 1.9 to 2. The refractive index of about 1 and the Si layer or the like is usually about 3.3 to 3.4. From the above, the refractive index of the wavelength conversion type solar cell encapsulant of the present invention is preferably 1.5 to 2.1, more preferably 1.5 to 1.9.

  By using a europium complex as the fluorescent material used for the wavelength conversion type solar cell sealing material of the present invention, a solar cell module having high power generation efficiency can be realized. The europium complex converts light in the ultraviolet region into light in the red wavelength region with high wavelength conversion efficiency, and the converted light contributes to power generation in the solar battery cell.

<Method for manufacturing solar cell module>
Using the sheet-shaped resin composition that becomes the wavelength conversion type solar cell encapsulant of the present invention, the wavelength conversion type solar cell encapsulant is formed on the solar cell to produce a solar cell module.
Specifically, it is the same as the manufacturing method of a normal silicon crystal solar cell module, and instead of the normal sealing material sheet, the wavelength conversion type solar cell sealing material (particularly preferably in the form of a sheet) of the present invention is used. .

  Generally, a silicon crystal solar cell module is first made into a sheet-like sealing material (mostly an ethylene-vinyl acetate copolymer with a thermal radical initiator on a cover glass which is a light receiving surface, and a thermosetting type. ). In this invention, the wavelength conversion type solar cell sealing material of this invention is used for the sealing material used here. Next, the cells connected by tab wires are placed, and a sheet-shaped sealing material (in the present invention, a wavelength conversion type solar cell sealing material may be used only on the light receiving surface side. And a back sheet, and a module using a vacuum press laminator dedicated to the solar cell module.

  At this time, the hot plate temperature of the laminator is a temperature necessary for the sealing material to soften and melt, wrap the cell, and further harden, and is usually 120 to 180 ° C., most of which is 140 to 160 ° C. Designed to cause these physical and chemical changes.

The wavelength conversion type solar cell encapsulant of the present invention is in a state before being made into a solar module, specifically, in a semi-cured state when a curable resin is used. In addition, the refractive index of the wavelength conversion type solar cell sealing material in a semi-cured state and the wavelength conversion type solar cell sealing material after being cured (after being formed into a solar module) is not greatly changed.
Although there is no restriction | limiting in particular in the form of the wavelength conversion type solar cell sealing material of this invention, It is preferable that it is a sheet form from the ease of manufacture of a solar module.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” and “part” are based on mass.

(Example 1)
<Synthesis of fluorescent substances>
200 mg of 4,4,4-trifluoro-1- (thienyl) -1,3-butanedione (TTA) was dissolved in 7 ml of ethanol, and 1.1 ml of 1M sodium hydroxide was added thereto and mixed. 6.2 mg of 1,10-phenanthroline dissolved in 7 ml of ethanol is added to the above mixed solution and stirred for 1 hour, and then a solution of 103 ml of EuCl ₃ · 6H ₂ O in 3.5 ml is added to obtain a precipitate. This was filtered off, washed with ethanol, and dried to obtain a fluorescent substance Eu (TTA) ₃ Phen.

<Production of spherical phosphor>
0.05 g of the fluorescent substance Eu (TTA) ₃ Phen obtained above, 100 g of methyl methacrylate, and 0.2 g of lauroyl peroxide as a thermal radical initiator were weighed and placed in a 200 ml screw tube. The mixture was stirred and mixed using a washer and a mix rotor. To a separable flask equipped with a condenser, 500 g of ion exchange water and 4 g of a 1.8% solution of polyvinyl alcohol as a surfactant were added and stirred. The liquid mixture of the methyl methacrylate prepared previously was added to this, and it stirred for 20 second at 2000 rpm using the homogenizer. While stirring at 350 rpm, this was heated to 60 ° C. and reacted for 3 hours. When the particle diameter of this suspension was measured using a Beckman Coulter LS13320, the volume average diameter was 104 μm. The precipitate was separated by filtration, washed with ion exchange water, and dried at 60 ° C. to obtain a spherical phosphor A by suspension polymerization.

The obtained spherical phosphor A was observed using a microscope or a scanning electron microscope, and it was confirmed that the obtained spherical phosphor A was spherical.
Further, when the methyl methacrylate constituting the spherical phosphor A was cured using the thermal radical initiator, the transmittance of light of 400 to 800 nm at an optical path length of 1 cm was determined to be 90% or more. .

<Preparation of resin composition for wavelength conversion type solar cell encapsulant>
As a transparent sealing resin (dispersion medium resin), 100 g of ethylene-vinyl acetate resin manufactured by Tosoh Corporation, Ultrasen 634, and a peroxide thermal radical initiator manufactured by Arkema Yoshitomi Co., Ltd. are used. 5 g, a silane coupling agent manufactured by Toray Dow Corning Co., Ltd., 0.5 g of SZ6030, and a mixture of 0.25 g of the spherical phosphor were kneaded with a roll mixer adjusted to 100 ° C. A resin composition for a solar cell encapsulant was obtained.

<Preparation of wavelength conversion type solar cell encapsulant sheet>
About 30 g of the resin composition for wavelength conversion type solar cell encapsulant obtained above is sandwiched between release sheets, a 0.6 mm thick stainless steel spacer is used, and a hot plate is adjusted to 80 ° C. I made it. The refractive index of the obtained sheet-form wavelength conversion type solar cell encapsulant was 1.5.

<Preparation of solar cell encapsulant sheet for back surface>
In the preparation of the wavelength conversion type solar cell encapsulant sheet, instead of the wavelength conversion type solar cell encapsulant resin composition, a resin composition prepared in the same manner as described above except that it does not contain a spherical phosphor. The solar cell encapsulant sheet for back surface was produced by the same method as above.

<Production of wavelength conversion type solar cell module>
The above-mentioned wavelength conversion type solar cell sealing material sheet is placed on a tempered glass (manufactured by Asahi Glass Co., Ltd., refractive index 1.5) as a protective glass, and the electromotive force can be taken out to the outside. The battery cell is placed so that the light-receiving surface faces down, and a back surface solar cell encapsulant sheet and a PET film (trade name: A-4300, manufactured by Toyobo Co., Ltd.) are placed as a back film, and a vacuum laminator is used. And laminating to prepare a wavelength conversion type solar cell module.
Note that a cell antireflection film having a refractive index of 1.9 is formed on the used solar battery cell.

<Evaluation of solar cell characteristics>
As a simulated solar ray, using a solar simulator (Wacom Denso Co., Ltd., WXS-155S-10, AM1.5G), current voltage characteristics using an IV curve tracer (Eihiro Seiki Co., Ltd., MP-160), In accordance with JIS-C8914, the short-circuit current density Jsc in the cell state before module sealing and the short-circuit current density Jsc after module sealing were measured and evaluated by taking the difference (ΔJsc). As a result, ΔJsc was 0.212 mA / cm ² . The measurement results are shown in Table 1 and FIG.
FIG. 4 shows the relationship between the amount of spherical phosphor contained in the wavelength-convertible resin composition layer and the power generation efficiency for each particle diameter of the spherical phosphor.

<Evaluation of luminous high temperature and humidity resistance>
Using a blue glass of 5 cm × 10 cm × 1 mm as protective glass in the same manner as in the above <Preparation of wavelength conversion type solar cell module>, the wavelength conversion type solar cell sealing material sheet is placed thereon, and a back film A PET film (manufactured by Toyobo Co., Ltd., trade name: A-4300) was placed thereon, laminated using a vacuum laminator, and this was used as a test piece.
The test piece was irradiated with 365 nm light using a handy UV lamp SLUV-4 manufactured by AS ONE Co., Ltd., and the presence or absence of red light emission was observed. Further, this test piece was placed in a constant temperature and humidity chamber adjusted to 85 ° C. and 85% relative humidity, and the presence or absence of red light emission was observed in the same manner as described above at an appropriate time. As a result, light emission was confirmed up to 2500 hours. The observation results are shown in Table 1.

(Example 2)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 1, the same procedure as above except that the content of the spherical phosphor A was changed to 0.5 g instead of 0.25 g In this method, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.499 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 3)
In <Preparation of resin composition for wavelength conversion type solar cell encapsulant> in Example 1, the same procedure and method as above except that the content of the spherical phosphor A was 3 g instead of 0.25 g Then, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.607 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

Example 4
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 1, the same procedure and method as above except that the content of the spherical phosphor was changed to 5 g instead of 0.25 g. , ΔJsc and luminous high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.474 mA / cm ² , and light emission was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 5)
In <Production of Spherical Phosphor> in Example 1, the suspension of the spherical phosphor was performed in the same manner as described above except that the blending amount of the fluorescent substance Eu (TTA) ₃ Phen was changed to 0.1 g instead of 0.05 g. A turbid liquid was obtained. When the particle diameter of this suspension was measured using a Beckman Coulter LS13320, the volume average diameter was 115 μm.
The precipitate was separated by filtration, washed with ion exchange water, and dried at 60 ° C. to obtain a spherical phosphor B by suspension polymerization.

The same procedure as described above except that 0.25 g of the spherical phosphor B obtained above was used as a spherical phosphor in <Preparation of resin composition for wavelength conversion type solar cell encapsulant> in Example 1. In this method, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.396 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 6)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 5, the same procedure as above except that the content of the spherical phosphor B was changed to 0.5 g instead of 0.25 g In this method, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.503 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 7)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 5, the same procedure and method as above except that the content of the spherical phosphor B was changed to 2 g instead of 0.25 g Then, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.557 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 8)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 5, the same procedure and method as above except that the content of the spherical phosphor B was changed to 5 g instead of 0.25 g Then, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.290 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

Example 9
Suspension of the spherical phosphor in the same manner as above except that the amount of the fluorescent substance Eu (TTA) ₃ Phen was changed to 0.5 g instead of 0.05 g in <Production of spherical phosphor> in Example 1 A liquid was obtained. The particle diameter of this suspension was measured using a Beckman Coulter LS13320. The volume average diameter was 113 μm. The precipitate was separated by filtration, washed with ion-exchanged water, and dried at 60 ° C. to obtain spherical phosphor C by suspension polymerization.
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 1, the same procedure as above except that 0.25 g of the spherical phosphor C obtained above was used as the spherical phosphor. In this method, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.387 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 10)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 9, the same procedure as above except that the content of the spherical phosphor C was changed to 0.5 g instead of 0.25 g In this method, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.437 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 11)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 9, the same procedure and method as described above, except that the content of the spherical phosphor C was changed to 2 g instead of 0.25 g Then, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.388 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Example 12)
In <Preparation of wavelength conversion solar cell encapsulant resin composition> in Example 9, the same procedure and method as above except that the content of the spherical phosphor C was 3 g instead of 0.25 g Then, ΔJsc and light emitting high temperature and high humidity resistance were evaluated. As a result, ΔJsc was 0.295 mA / cm ² , and luminescence was confirmed up to 2500 hours. The measurement results and observation results are shown in Table 1 and FIG.

(Comparative Example 1)
In Example 1 <Preparation of resin composition for wavelength conversion type solar cell encapsulant>, except that 0.01 g of the fluorescent substance Eu (TTA) ₃ Phen was used as it was instead of the spherical phosphor A, the above ΔJsc and light emitting high temperature and high humidity resistance were evaluated by the same procedure and method as described above. As a result, ΔJsc was −0.18 mA / cm ² , and no luminescence was confirmed after 24 hours. The measurement results and observation results are shown in Table 1.

In Table 1, the phosphor content indicates the content of the phosphor in the spherical phosphor, and the blending amount is the spherical phosphor (Examples 1 to 12) or the phosphor (Comparative Example 1) with respect to 100 parts of the transparent sealing resin. The number of blended parts is shown.
From Table 1, by constructing a solar cell module using the wavelength conversion type solar cell encapsulant containing the spherical phosphor of the present invention, the light utilization efficiency in the solar cell module is improved and the power generation efficiency is stably improved. It became possible to make it.

Claims (10)

As a fluorescent substance, a europium complex having at least one organic ligand selected from carboxylic acid, nitrogen-containing organic compound, nitrogen-containing aromatic heterocyclic compound, β-diketone, and phosphine oxide;
Transparent (meth) acrylic resin as a transparent material,
Volume average diameter Ri 10μm~500μm der,
The fluorescence wavelength converting solar cell encapsulant spherical phosphor content of Ru to 1% by mass 0.001% by weight of the material.   The spherical phosphor according to claim 1, wherein a refractive index of the transparent material is lower than that of the phosphor and is 1.4 or more.   The spherical phosphor according to claim 1 or 2, wherein the vinyl monomer composition in which the fluorescent substance is dissolved or dispersed is spherical resin particles obtained by suspension polymerization.   A wavelength conversion type solar cell sealing material provided with the light transmissive resin composition layer containing the spherical fluorescent substance of any one of Claims 1-3, and sealing resin.   The wavelength conversion type solar cell sealing material according to claim 4, wherein a content of the spherical phosphor in the resin composition layer is 0.0001 to 10 mass percent.   The wavelength conversion type solar cell sealing material according to claim 4, further comprising a light transmissive layer other than the resin composition layer. M layers composed of the resin composition layer and a light transmissive layer other than the resin composition layer are provided, and the refractive indexes of the m layers are set to n ₁ and n _{2 in} order from the light incident side. _{, ···, n (m-1} ), when the _{n m, n 1 ≦ n 2} ≦ ··· ≦ n (m-1) is ≦ _{n m,} the wavelength conversion type according to claim 6 Solar cell encapsulant.   A solar cell module provided with a photovoltaic cell and the wavelength conversion type solar cell sealing material of any one of Claims 4-7 arrange | positioned on the light-receiving surface of the said photovoltaic cell. The step of obtaining a spherical phosphor according to any one of claims 1 to 3 by suspension polymerization of a vinyl monomer composition in which a fluorescent substance is dissolved or dispersed;
A sheet forming step of forming a resin composition obtained by mixing or dispersing the spherical phosphor in a sealing resin into a sheet; and
The manufacturing method of the wavelength conversion type solar cell sealing material which has this.   It is a manufacturing method of the solar cell module which has a some light transmissive layer and a photovoltaic cell, Comprising: The wavelength conversion type solar cell sealing material of any one of Claims 4-7 is used as a photovoltaic cell. A method for manufacturing a solar cell module, comprising the step of forming one of the light-transmitting layers by disposing it on the light receiving surface side.